The present invention relates to a contact block of a chip card reader having a contact carrier and contact elements arranged therein, the contact elements each comprising a contact section, an intermediate or joining section which is enclosed by said contact carrier and a terminal section.
A contact block for a chip card reader of the above type is for example known from U.S. Pat. No. 5,013,255. The contact block is formed by cutting contact elements from a strip of sheet metal such that they have a free end (contact end) and an opposite end (terminal end) which is connected to a pilot strip in order to hold the contact elements in the stamped arrangement. An intermediate section extends between the opposite ends of the contact elements. In a further manufacturing step, the intermediate or joining sections of the contact elements are enclosed by material for forming a contact carrier, using an injection molding technique. Finally, the pilot strips are removed from the contact elements. The contact block comprises two sets of contact elements which, project into cut outs in said contact carrier from opposite sides and the contacts elements are guided out of said contact carrier at the opposite sides of the contact carrier.
The terminal ends of the contact elements are formed as soldering contacts. In view of the detrimental effects to the environment related to the soldering of such contacts, there is a tendency to form the terminal ends into pressure contacts, i.e. contacts which are simply pressed against respective contact elements without the need of soldering or other forms of attachment. The use of pressure contacts, however, increases the forces acting on the contact carrier in view of the inherent spring force of the pressure contacts. These forces, however, are capable of damaging conventional contact blocks in view of their low stiffness.
It is therefore an object of the present invention to provide a simple and inexpensive contact block for a chip card reader which comprises good durability and stiffness.
In one aspect of the invention, a contact block for a chip card reader having a contact carrier and contact elements arranged therein is provided. The contact elements each have a contacting section, an intermediate or joining section, which is enclosed by said contact carrier, and a terminal section. The intermediate sections are formed as a stiffener or reinforcement for the contact carrier, at least one of the intermediate sections has at least one bend (i.e. a portion of the intermediate sections, where a change of orientation occurs) within the plane of the contact carrier and is bent by at least 90xc2x0. The at least one intermediate section which is bent by at least 90xc2x0 within the plane of the contact carrier provides longitudinal as well as transverse stiffening for the contact carrier, thus increasing the overall stiffness thereof. The at least 90xc2x0 may be achieved by more than one bend.
Using the intermediate section of the contact elements as stiffeners, the stiffness of the contact carrier may be increased in a simple and cost effective manner, without increasing the thickness of the contact bock and without the use of separate elements. At least one of the contact elements preferably comprises a broadening in the intermediate section compared to the contacting section. Due to the broadening, a larger area of the contact carrier comprises a core formed by the contact elements, thus increasing the stiffness.
In one aspect of the invention, a contact block for a chip card reader having a contact carrier and contact elements arranged therein is provided, wherein the contact elements each have a contacting section, an intermediate or joining section, which is enclosed by said contact carrier, and a terminal section, the intermediate sections being formed as a stiffener for the contact carrier, the contacting sections of the contact elements extend from different directions into a contact area formed in the contact carrier and all the terminal sections extend from a common side of the contact carrier. Having the terminal sections of the contact elements extending form a common side of the contact carrier enables easy connection of the contact block to a housing for receiving said contact block.
According to a preferred embodiment of the invention at least one of the intermediate sections comprises at least one bend within the plane of the contact carrier, in order to achieve increased stiffening effects in different directions of the contact carrier. Preferably, at least one of said intermediate sections is bent by at least 90xc2x0 within the plane of the contact carrier in order to provide longitudinal as well as transverse stiffening of the contact carrier. Preferably, at least one of the intermediate sections comprise more than one bend within the plane of the contact carrier in order to achieve a good stiffening effect.
In a further embodiment of the invention, at least one of the contact elements has a stiffening arm providing a stiffening effect outside of the connecting path of the intermediate sections. The stiffening arm extends into areas of the contact carrier in which no intermediate sections of the contact elements are present in order to provide an additional stiffening effect in these areas of the contact carrier.
Preferably, at least one of the intermediate sections comprises a cusp in order to achieve a higher stiffening effect.
The contact carrier preferably has a common opening into which the contact sections of the contact elements extend. The opening has a suitable form and size which enables the contact elements to act as springs. The contact sections of the contact elements preferably extend from opposite sides into the opening, and are interleaved, thus enabling in a simple manner a two-row arrangement of contact cusps with the contact sections each providing a sufficient spring arm.
In a preferred embodiment of the invention, the terminal sections of the contact elements extend from a longitudinal side of the contact carrier, thus decreasing the mounting depths of the contact block. Further, when the contact elements extend from a longitudinal side of the contact carrier, the intermediate sections extend at least partially transverse to the contact carrier, thereby providing good transverse stiffening of the contact carrier. In an alternative embodiment of the invention, the terminal sections of the contact elements extend from a transverse side of the contact carrier which is advantageous for use in a housing having a small width.
The contact elements are preferably stamped portions which are preferably stamped from a sheet metal for easy and inexpensive manufacture thereof. The contact elements are preferably arranged in a stamping grid, i.e. they are stamped directly in a single stamping process into the arrangement of their later use, thus avoiding complicated arrangement of the elements in a later step. Preferably, at least one of the contact elements is connected to a pilot strip of the stamped sheet metal in order to permit easy transport of the contact block via the pilot strip. Separate packing for the contact blocks is not necessary, since they may be held by the pilot strip and may be delivered to the customers with said pilot strip.
In accordance with a preferred embodiment of the invention, the contact carrier comprises a raised corner portion for the chip card in order to provide good guidance and reception of said chip card.